Prairie View A&M University HBCU/MI Environmental Technology Consortium Hylton G. McWhinney, Ph.D. Principal Investigator John R. Williams, Ph.D. Steering Committee Member March 10, 2003

A Study of Sediment Composition and its Effects on Hazardous Metal Ion Sorption Brief project background Research Goals and Objectives Specific Studies of Interest Project Deliverables

Project Background Knowledge of sorption and partitioning of heavy metal ions on particles is fundamental to the understanding of transport mechanisms and the fate of these contaminants in the environment. X-ray photoelectron spectroscopy (XPS) studies are useful in delineating the effects of solution chemistry (concentration, competing ions, and pH) on selected highly toxic metal ions.

Project Background The adsorption in soils of toxic metal ions such as Cr, Zn, Cu, Pb, and Cd, as well as radioactive ions and their analogs, is of tremendous importance. Although, these ions may adsorb at low concentrations, colloid aggregation and sedimentation may result in concentrating these materials in sediments. Pesticides, metals, chlorinated hydrocarbons and other contaminants absorbed to particles carried by rivers may be transported to the sediments of lakes and estuaries.

Project Background Previous work has relied upon “bulk” characterization of metals. Detailed surface and interfacial analysis and the processes controlling metal adsorption and transport have not been thoroughly addressed so far. In natural systems, mixtures of inorganic solutes compete for adsorption sites on particles. The nature of this competition determines the ultimate distribution of metals between dissolved and colloidal phases.

Project Background Process is more complex in systems such as the Houston watershed, where particles and contaminants undergo a drastic change in solution chemistry as they are transported to the more saline estuarine environment. Adsorptive equilibria and colloidal stability may change. The relationship between adsorption of inorganic species and colloids stability is of particular interest since aggregation may enhance the transport of adsorbed species in sediments.

Research Goals and Objectives Project is designed to Increase understanding of the role of sedimentation in the transport and build up of toxic metals in lakes, harbors, and estuaries. Primary Objective is to study the surface compositions of natural particles and to investigate their effects on competitive adsorption of hazardous metal ions (Zn, Pb, Cu, Cr) on colloids and sediments.

Proposed Studies It is proposed to carry out surface and bulk studies on: –Competitive adsorption and desorption of selected metal ions on sediments of 1µ - 250µ size distributions. Particular interest will be placed on the behavior of particle sizes less that 5µ because these represent particles of great interest. –Sorption on particles in the presence of simulated waste runoff. –Sorption on sediments in estuarine conditions (Various degrees of salinity and ionic strength media). –The use of X-ray Photoelectron Spectroscopy to establish the elemental composition (semi-quantitative) of sediments on a routine basis.

X-Ray Photoelectron Spectrometer PHI 5600ci XPS/ISS Instrument located in the Surface Science Facility of the Department of Chemistry at PVAMU

Expected Project Deliverables Required Quarterly and Annual Reports, Manuscripts for publication and presentations at regional and national professional meetings. Undergraduate and Graduate Student, Staff, and Faculty development.